In order to stabilize service of a power system, various types of devices have been utilized to detect occurrence of outages or malfunctions in the power system. For example, an intelligent electronic device (IED) is configured to (i) acquire results of measurement of voltage value and current value in the power system from a current transformer (CT), a potential transformer (PT) (or voltage transformer (VT)), and the like, (ii) detect occurrence of overvoltage, shortage of voltage, overcurrent, or the like due to failure or the like, and (iii) send a control signal to a circuit breaker. Accordingly, a countermeasure can be immediately taken by, for example, separating the failed section from the power system.
Since such an intelligent electronic device requires high reliability, the intelligent electronic device is subjected to various performance check tests in various aspects, for example, before shipment or during service.
Japanese Patent Laying-Open No. 2011-155779 (Patent Document 1) describes a digital protective power relay device having a testing function. In this digital protective power relay device, a digital relay is provided with a memory in which data of voltage waveform or current waveform corresponding to power system failure and input conditions such as device conditions in the power system side are written beforehand. This digital protective power relay device is provided with a switch, which is externally switchable to read out either (i) an amount of analog input acquired from the power system side or (ii) the waveform data written in the memory. The relay device is verified by: switching the switch to the side of the memory having the waveform data written therein; sequentially reading out the waveform data from the memory at a sampling cycle of the protective relay; and performing calculation for the relay in accordance with the data thus read out. Accordingly, a similar effect is obtained as with the case of externally applying current and voltage waveforms for simulating power system failure by utilizing a simulation power transmission line.
Japanese Patent Laying-Open No. 2012-249387 (Patent Document 2) describes the following technique: in a power system protection control system employing a process bus, for the purpose of a test, a testing device is connected to the process bus, and the testing device outputs, to an intelligent electronic device via the process bus, test electric quantity information having a test flag added therein. Based on the test electric quantity information received from the testing device, the intelligent electronic device determines whether to trip a circuit breaker. If it is determined to trip, the intelligent electronic device outputs to the process bus a test trip command having the test flag added therein. When a merging unit (MU) receives the test trip command via the process bus, the merging unit determines that the operation of the intelligent electronic device outputting the trip command is normal.